Primary progressive aphasia (PPA) is an adult onset disease that selectively attacks the left hemisphere language network. Despite considerable progress in this field, patients with PPA and their families remain underserved. Accurate medical diagnosis can be challenging outside of specialized centers, relevant educational materials are scarce, few speech and language pathologists in the community are equipped to provide informed interventions, and many patients tend to be excluded from clinical trials because the complex relationship to underlying neuropathology is not fully appreciated. This proposal comes from a team of investigators with a primary focus on PPA. It seeks to pursue a research program that is now in its 10th year and that has recruited nearly 150 patients for longitudinal investigation. As a consequence of the proposed work we expect to sharpen our understanding of lexicosemantic and grammatical impairments experienced by the patient, obtain new insights into the organization of the left-hemisphere language network, clarify the diagnostic fingerprints of PPA caused by Alzheimer?s disease versus frontotemporal degenerations, and increase the precision with which we can trace the temporal trajectory of the disease. The work will also continue to generate collateral benefits in the form of new educational materials for patients and families, improved recognition of the syndrome, potentially greater access of PPA patients to relevant clinical trials, and the training of students and fellows who will develop into the next generation of clinicians and investigators serving the needs of patients with PPA.